Google Map - Need to create Callback to get params

Hello all, I had a developer create custom code for a polygon search for a real estate site. I need to create a call back to get 4 parameters. Please take a look at my page at http://www.oasischicago.com/chicago/pilot . The custom code is linked under arck_polysearch.js . Any advice would be helpful. The parameters I need are lat_min, lat_max, lng_min, lng_max.

Thanks in advance. The developer had a callback but it was in php. I'll attach it but dont know if its usable since outsystems is in .Net.